Award Winning Shoring Key to Success

In recognition for the successful collaboration and the innovative shoring design, this project was awarded the 2020 Scaffolding & Access Industry Association (SAIA) Shoring Project of the Year.

Originally built in 1962, Climate Pledge Arena (originally known as Key Arena) is located in the heart of the historic Queen Anne district of Seattle. To take advantage of its prime but densely populated location, the arena was built down into the ground, with a pavilion-like sloping roof that has become a staple of the Seattle skyline. As part of a $700 million remodel, the Seattle Center Arena would get entirely new facilities, meaning the entire interior structure of the arena would be demolished and rebuilt from the ground up. With the majority of the arena built underground, this meant the existing concrete retaining walls would no longer have the concrete floors to support them and would require soil anchors be installed for support. In order to install those new soil anchors, an 18,000 lb micro pile drilling machine had to be driven on the existing slabs. However, the drill rig was a load the slab was never designed to support.

Due to the rapid pace of construction, it was immediately clear that coordination and clear communication would be required for the project to succeed. DHC was met on site by scaffolding contractor Performance Contracting, Inc.,  as well as representatives of both the general contractor and the structural engineer (SEOR) for the structure. The site to be shored was walked extensively, with each party noting critical locations that either needed to be shored, to be left open for access, or obstructions that needed to be worked around. The area of highest concern was over the Event Level ramp. The SEOR made it clear the Main Concourse slab above the ramp need to be shored to support the drill rig. At the same time, the general contractor was adamant that the ramp had to stay open and unimpeded in order for construction to stay on schedule. With demolition well underway, the ramp saw a constant stream of dump trucks as material was moved out of the stadium. The scope was to design a shoring system that fully supported the upper slab while taking up no space on the floor below.

After exploring some initial options, it was eventually determined that the most feasible way to adequately support the Main Concourse slab while simultaneously leaving the ramp open would be to essentially build a “tunnel” in the shoring; the slab itself would be shored up using modular cuplok scaffolding, which would then be set onto large steel beams spanning the width of the access ramp. After confirming the type of drill rig that would be used, DHC performed a detailed moving load analysis of the drill rig to model the loading that would be applied to the shoring. This drastically reduced the load on any one shoring beam, allowing for the use of lighter, more easily erectable beams.

Due to the slab above the ramp dropping as the ramp descended, as well as the presence of concrete beams at awkward angles, the modular, flexible nature of cuplock scaffold was used to its fullest as the main support of the Main Concourse slab. To support the steel beams on either side of the ramp, RMD Kwikform Super Slims were used as vertical post shores. While originally designed for use in falsework and concrete wall pouring applications, the Super Slims had high axial capacity and DHC had experience in using them in shoring applications. By bracing them to each other, as well as anchoring them to concrete wall and ramp for stability, a stabile base for the shoring tunnel was created that took up less than a foot of width. Once fully installed, the tunnel shoring allowed for the tie back installation to successfully move forward without any hinderance to the demolition work.

Mark Palmatier, PE – Branch Manager – (425) 559-9775

Jasper Calcara, PE – President – (760) 436-9756

Chicago Office Opening


D.H. Charles Engineering, Inc. has a long-standing tradition of servicing clients in the State of Illinois since obtaining our IL SE license, and has developed close relationships with contractors, IDOT and CDOT OUC over the past twenty years working in the area.  Even though we’ve felt confident we could continue to meet the needs of our customers, as had been proven with the hundreds of projects completed, we knew a local presence would provide the extra level of support we wished to offer.  Therefore, after many years of looking for the right opportunity we are thrilled to announce the opening of our newest office in Chicago.

Andrew Schwarz, PE, SE, was born and raised in the Chicagoland area and continues to call the area home. He has over twenty years of experience in the structural and geotechnical engineering discipline, including starting out in the bridge design industry while also working in the building design industry.  For the last 10+ years, he has been working in the underground shoring and temporary works industry expanding his close relationships with contractors in the area.   Andy is excited to be joining the DHC team and looks forward to growing the Chicago and Midwest operations for the company while assisting the company nationwide.


The success of the Seattle, Portland and New York offices has proven that although our resources are now spread throughout the Country, we can effectively work as a team and can be depended upon to share our wealth of design experience and knowledge regardless of location.  Our customers have come to expect collaboration and support from all our team members in developing state of the art and cost-effective solutions for their construction engineering needs.


Andy and the entire DHC team look forward to servicing an expanded customer base and providing more on-site support to projects in the area.  Please contact any of our team members to discuss how we can be of assistance on your jobs or bids.

Andrew Schwarz, SE, PE – Branch Manager/Sr. Engineer – (872) 240-8033

Jasper Calcara, PE – President – (760) 436-9756

Luke Griffis, SE, PE – Vice President – (707) 537-8282


East Coast Office Opening


After successfully servicing clients on the East Coast for over 20 years, D.H. Charles Engineering, Inc. is excited to announce the opening of its newest office in New York City.  Although originally founded and headquartered on the West Coast, DHC has worked tirelessly to prove to its customers that regardless of location or time-zone, excellent service can be counted on day after day.  A culture of immediate response to all calls, and expert support by experienced engineers, has resulted in long and valued relationships with our national accounts.


Branch Manager and Sr. Design Engineer Chong Kim, P.E., has developed personal relationships with contractors throughout the greater NY, NJ and New England areas for over a decade.  His experience in design of complex excavation shoring systems, along with many other temporary works designs, made him an excellent fit for heading DHC’s expansion East.  He’s passionate about what he does, and brings innovative design ideas to his projects, with a positive and creative attitude.


New NY Bridge – Photo By: New York State Thruway Authority

The success of the recently opened Seattle office has proven that although DHC resources are now spread throughout the Country, they can effectively work as a team and be depended upon to share their wealth of design experience and knowledge regardless of location. Their customers have come to expect collaboration and support from all team members in developing state of the art and cost-effective solutions.

DHC looks forward to servicing an expanded customer base and providing more on-site support to projects in the area.  Please contact any of our team members  to discuss how we can be of assistance on your jobs or bids.

Chong Kim, PE – Branch Manager/Sr. Engineer – (914) 292-4337

Jasper Calcara, PE – President – (760) 436-9756

Luke Griffis, SE, PE – General Manager – (707) 537-8282


Support Under Distress


The 6.0 magnitude Napa Earthquake struck on August 24, 2014,  and caused substantial damage to many structures in this popular tourist destination.  DHC received many calls during the aftermath of the earthquake, as the damage was widespread and structures were in need of temporary support.  Bracing and shoring was deemed necessary for many building simply to allow personnel to gain access, retrieve belongings, or survey the true extent of the destruction.

One building that was hit particularly hard was the Historic Napa Courthouse located downtown on Brown Street.  D.H. Charles Engineering, Inc. was contracted to develop a wall bracing system that could be installed without positive anchorage to the wall itself.  This was imperative, as the competence of the wall was unknown and workers could not be exposed to a potential collapse during bracing installation.  The resulting system consisted of vertical I-beams that were rotated upwards against the wall, and then diagonally braced with tilt-up braces anchored to the wood floor joists.  This scheme and installation process provided the necessary safe working environment, and ultimately allowed for temporary scaffold towers to be placed inside the room which provided temporary support to the roof.


DHC was also contacted by RMB Management Company to come up with a solution to recover personal items for customers of the heavily damaged two-story self-storage building at the Napa Self Storage facility.  The entire second story had  shifted out of alignment from its foundation such that the first story walls were heavily skewed and damaged.  The primary challenge was not being able to visibly see the full extent of the damage without first stabilizing the whole building and providing safe access to the structure.


Our first step was to design an exterior bracing system at the second floor, for global stabilization, and relieve load to the damaged interior walls.  We then designed an extensive plan to incrementally provide internal access to the lower floor units.  Modular scaffold shoring would be used throughout the building’s access points to simultaneously shore the lower level while providing safe entry for workers to evaluate the extent of the damage, recover personal belongings, and provide additional shoring within the storage units as necessary to stabilize the structure.

DHC enjoyed the opportunity to support their neighbors in a time of need, and help the residents and businesses of Napa return to normal life.

DHC Expands to Seattle Area

After much planning and the steady encouragement of many of our customers, DHC is proud to announce the opening of an office in the greater Seattle area.  With main branches in Santa Rosa & San Diego, and satellite offices in Oakland & Sacramento, the Seattle location becomes the 5th for DHC.

This new office is being managed by John Meissner, PE, who is a native of the Pacific Northwest and is excited about the opportunity to meet with many customers personally in coming months.

Even without local branches, DHC has maintained a tradition of effectively servicing contractors throughout the US and Canada, and has developed long-lasting relationships with many of them.  Nonetheless, we look forward to the opportunity to meet many new and existing customers in person, and plan to host various training programs and introductory meetings in the coming months and years.

If you would like to learn more about DHC, or to meet in person, please do not hesitate to contact John Meissner, President Jasper Calcara, or General Manager Luke Griffis.

Partial List of Engineering Services Provided:

  • Excavation Shoring/Safety
  • Tunneling and Boring
  • Scaffold Structures
  • Bridge Jacking and Support
  • Suspended Platforms
  • Crane and Rigging
  • False/Formwork
  • Structural Shoring
  • Re-shore
  • Fall Protection
  • Rebar Cage Stabilization
  • Containment Design





Industry Leader – Guest Lecturer – UCSD

D.H. Charles Engineering, Inc. (DHC) was invited to be a guest lecturer for roughly 120 graduating seniors of the University of California San Diego (UCSD) Structural Engineering department.  With an established passion for educating the construction industry in engineering challenges and safety, DHC was more than happy to accept the invitation, and had the perfect candidate to send to the classroom.


Chong Kim, P.E., a senior engineer and alumni of the same program at UCSD, has worked on thousands of construction engineering designs throughout the US and Canada in his career at DHC.  He took that experience on a wide variety of projects, and developed a presentation titled Temporary Structures and Construction Engineering Industry, to present to students taking the SE140 course.

2015-05-07 10.03.39

SE140: Structures and Materials Laboratory, introduces students to real world challenges and applications of structure design, including: Problem formulation, concept design, configuration design, project management, team working, ethics, and human factors.  –UCSD Course Curriculum

The variety of situations and challenges faced on a construction site can be overwhelming, with many codes and design approaches never discussed at the University.  Therefore, the presentation narrowed the field of construction engineering and focused in on the following key areas:

  • Excavation Shoring
  • Construction Slopes
  • and Slope Stability Analysis
  • Tunneling and Boring
  • Scaffold Structures
  • Bridge Jacking and Support
  • Suspended Platforms
  • Crane and Rigging
  • False/Formwork
  • Structural Shoring
  • Re-shore
  • Fall Protection
  • Rebar Cage Stabilization

Most students do not have the real-world experiences that come with time and that are hard to find in text books, so it was important to illustrate each subject area with as much photographs, colorful anecdotes, and challenges that were faced on particular projects.

excavation shorint

It was important to Chong that he connected with the students on a personal level, as he could clearly recall sitting in their position all those years ago.  He focused on the challenges and fears all young professional faces when starting their first jobs, as well as how to evolve as the their careers take them in different directions.  But most importantly, he wanted to exemplify how important it is to continue to take on challenges and overcome their professional and personal fears.  Presenting in front of peers was a first for Chong, and something he was very proud of accomplishing.

There were many insightful questions from students throughout the presentation, showing that they were truly interested in and engrossed with the subject matter.  The open discussions covered many aspects of construction engineering, codes, loads, workplace environment, as well as general challenges facing engineers in today’s world.


Evoking passion for what we do as engineers is the most important thing an educator can do, and based on the enthusiasm and response of the students, we are hopeful we were able to accomplish this.  We want to extend a special thank you to Professor Lelli Van Den Einde, Ph.D. for bringing us into her classroom and organizing the guest lecturer opportunity, and wish the best of luck to the class of 2016!


Mega Brace Shoring Provides Unique Solution For Water Project

This article was originally published in Underground Construction Magazine in December 2010.

Mega Brace Shoring Engineering ProjectProjects requiring excavation are recognized as among the most dangerous in construction, and protecting personnel who must work in trenches and surrounding areas from cave-ins is a priority with life and death implications.

For small jobs, trench protection may be as simple as dropping a trench box into the excavation. Larger jobs are more complex. A major project often requires extensive engineering and the use of specialized shielding and shoring.

North America’s largest rental supplier of trench safety systems and products is United Rentals. The company also is a provider of pre-construction planning and turnkey installation and removal services. United Rentals operates more than 50 trench safety rental branches that offer the latest technologies in steel and aluminum trench shields, aluminum trench shores, steel sheet pile with modular waling systems, steel crossing plates and custom slide rail systems.

Recently, United Rentals provided a Mega Brace shoring system for an Xcel Energy project in Colorado to pull water from the South Platte River downstream from Denver at the discharge point of the Denver Metro Wastewater Treatment Plant, and divert it to the company’s Cherokee Power Plant approximately half a mile away.

General Contractor was Garney Construction, Littleton, CO. Working as a subcontractor to Garney, Territory Unlimited, Berthoud, CO, built a grouted boulder drop structure in the South Platte River that was integrated with a Garney-installed concrete diversion structure and 170 linear feet of 24-inch ductile iron pipe to bypass water to a pump station wet well structure.

Territory Unlimited installed the Mega Brace system with teams of United Rentals personnel providing expertise on site throughout the project.

The Mega Brace system was engineered by D. H. Charles Engineering, Santa Rosa, CA, and was used in a 30-foot deep, four-sided 35-by-30-foot excavation for construction of a 25-foot high, 25-by-20 foot concrete wet well structure, said Kris Graham, United Rentals outside sales representative, Denver.

Graham said a sloping system was ruled out because it would have required removal of more than 4,666 cubic yards of soil, compared to the 1,166 cubic yards for the Mega Brace.

Other bracing systems were evaluated and rejected.

“Beam and plate,” said Graham, “would require counter sinking the beams below the bottom grade, but the soil reports indicated extremely hard materials that would have been very slow for the required caisson drilling. We had the same issues with the sheet pile options, but were able to engineer it without the toe in.”

Graham said slide rail was an option that could have been made to work, but would have required multiple sets of cross struts running both north/south and east/west. Not only would the installation have been longer due to the excavator needing to work around the cross struts, it would have required the concrete crew to work around these cross struts and then have an excavator on stand-by to pull them up as the concrete structure progressed.

Sheet pile with conventional I-beams welded to sheet pile would have achieved the same results, Graham continued, but would have required certified welders to cut and weld the rings/levels of I-beam and cut and grind them from the sheet pile at the time of removal. This would have required an estimated one-day per ring/level and downtime of crew and equipment to swing the I-beam to welders.

“Instead, the Mega Brace system was installed with the same size crew and equipment in an average of two hours per ring/level, saving close to one week on the installation and the cost of the certified welders,” Graham said.

Manufactured by Ground Force Engineering, Harrogate, North Yorkshire, England, the Mega Brace takes the place of conventional I-beams for use as a waler system in a sheet pile/beam and plate installation, said Graham.

“Mega Brace,” he said, “has pre-manufactured lengths of I-beam and cross struts that have the ability to quickly pin together to fit the length or width required for the construction project. What makes the Mega Brace system unique compared to I-beam walers is that a six-inch telescoping hydraulic ram is pinned to the ends of the I-beam extensions or struts. This allows the system to pump in or out to fit the excavation and hold the system in place without the required welding to the sheet pile required of a conventional application.”

When the project was bid, said Graham, United Rentals had 90 percent of the Mega Brace equipment required on hand. By the time work was ready to begin, equipment was committed to other projects, and United Rentals transferred equipment from Florida and Georgia for the Colorado project.

Graham said that to install the bracing, Garney Construction first pre-drilled a series of 30-foot deep dewatering well points around the excavation site. In accordance with the engineer’s design, five feet of soil was excavated from the top and sloped back.

“One of the Mega Brace ring/levels was assembled with the hydraulic rams pulled in smaller than the finished pit size,” he continued. “This was used as a template for the sheet pile being driven. After all the sheeting had been driven to grade/point of refusal, Territory Unlimited crew members excavated the pit seven feet with the Mega Brace ring/level going down at the same time. At this point the Mega Brace hydraulic rams were pumped out one at a time in all four corners.”

Safety chains were then secured from the Mega Brace to the top of the sheet pile. Territory Unlimited excavated another seven feet and the four legs of the Mega Brace were lowered into the pit and pinned together and the four hydraulic rams pumped out to lock the system into place.

“Safety chains were attached again,” Graham continued. “We repeated the process with a double stacked ring/level of Mega Brace seven feet below the middle ring. At this point, Territory Unlimited completed the excavation to final grade.”

Three days were required to drive the sheet pile, and it took five days to install the four rings/levels of Mega Brace to the 25-foot depth. Excavation of the remaining five feet and completing the finish grade took another two days.

Soil conditions were sand and gravel. “The soil type made for a relatively simple installation,” said Graham. “The challenges of the project were the depth of the excavation and dewatering necessary because of the close proximity to the river.”

United Rentals provided two teams on this project to make sure things went as smoothly as possible.

Graham said Mega Brace system has been used in the United Kingdom and Europe for 30 years and was brought to the Unites States about five years ago.

“United Rentals Trench Safety Branches have been installing Mega Brace systems for five years,” Graham said. “This project would be considered moderately-sized compared to some of the projects United Rentals Trench Safety has done on the east coast. During the field and classroom training we did with Ground Force Engineering personnel from England, we saw projects with entire city blocks excavated 50 feet deep in London using the hydraulic Mega Brace and cross strut systems. Garney and Territory Unlimited are the first to use the system in Colorado. Both companies were great to work with.”

United Rentals is the largest equipment rental company in the world, with an integrated network of 549 rental locations in 48 states and 10 Canadian provinces. The company’s approximately 7,400 employees serve construction and industrial customers, utilities, municipalities, homeowners and others. The company offers for rent approximately 2,900 classes of equipment with a total original cost of $3.8 billion.

In addition to shielding and shoring equipment, United Rentals’ trench safety branches also carry confined space ventilators, detectors and other equipment and offer 24-hour emergency response and professional safety training.